The present invention relates to a chair and, more particularly, to a chair including a backrest for supporting most weight of a body of a user when the user moves from a sitting posture to a lying posture, providing lying comfort and enhanced supporting stability.
Conventional chairs generally include a reclining device to increase sitting comfort. FIG. 9 shows a conventional chair including a base 1′, a seat 2′, and a backrest 3′. An armrest 11′ is mounted to an upper portion of each of two sides of the base 1′. A guiding rod 12′ is mounted to a central portion of each side of the base 1′. A sliding sleeve 21′ is mounted on each guiding rod 12′ and located in front of the base 1′. The seat 2′ includes a pivotal portion 22′ at a rear thereof. The backrest 3′ includes a lower end having a pivotal portion 31′ pivotably connected to the pivotal portion 22′ of the seat 2′. The backrest 3′ further includes another pivotal portion 32′ pivotably connected to a rear end of each armrest 11′. Thus, an angle between the backrest 3′ and the seat 2′ is small when the chair is in a substantially upright position. The backrest 3′ can be moved to a reclining position while moving the seat 2′ forward. Each sliding sleeve 21′ can be moved to a front end of a corresponding guiding rod 12′. As a result, the angle between the backrest 3′ and the seat 2′ in the reclining position is larger than the angle in the substantially upright position.
However, an inclination angle θ1 of the seat 2′ in the reclining position is small such that most weight of a user lying in the chair is supported by the seat 2′, failing to provide lying comfort.
FIG. 10 shows another conventional chair including a base 4′, a seat 5′, and a backrest 6′. A legrest 51′ is provided on a front end of the seat 5′. A spring 52′ is attached between the seat 5′ and the base 4′. The backrest 6′ is at a fixed angle to the seat 5′ and includes a pivotal portion 61′ pivotably connected to the base 4′. When a user lies down against the backrest 6′, the backrest 6′ and the seat 5′ pivot at the pivotal portion 61′ and stretch the spring 52′ to restrain the reclining position of the backrest 6′. An inclination angle θ2 of the seat 5′ relative to the ground can largely be increased such that most weight of the user is imparted to the backrest 6′, providing an effect similar to weightless turn while providing enhanced lying comfort.
However, the center of gravity is shifted to a position behind the base 4′ when the seat 5′ pivots backward together with the backrest 6′, leading to risks of falling of the whole chair due to an unstable center of gravity. Furthermore, the inclination angle θ2 of the seat 5′ is larger than that of an average user lying flat, causing discomfort to the user.